1. Field of the Invention
This invention relates to a dispenser for selectively extending and retracting a substantially stick-shaped object, such as a rubber eraser, lead crayon, a pastel, glue, chalk, rouge or eyebrow pencil lead, and a writing instrument, e.g., a mechanical pencil, a ball-point pen, a sign pen or a marking pen, equipped with such a dispenser.
2. Description of the Prior Art
U.S. Pat. No. 5,234,275, Gueret, issued Aug. 10, 1993, discloses a holder for delivery or retraction of a product stick in the direction of rotation of a tubular element with respect to a casing through an outlet end of the tubular element. The conventional holder has a room for housing the product stick but has no room for storing a spare product stick. If the holder has such a room for storing a spare product stick, it may be helpful to easily and always replace the product stick, which becomes shortened by consumption, with spare product stick stored in the additional room.
U.S. Pat. No. 5,022,774, S. Kageyama et al., issued Jun. 11, 1991 and assigned to the assignee of the present application, U.S. Pat. No. 5,062,727, S. Kageyama et al., issued Nov. 5, 1991 and assigned to the assignee of the present application, U.S. Pat. No. 5,207,522, S. Kageyama et al., issued May 4, 1993 and assigned to the assignee of the present application, U.S. Pat. No. 5,236,270, S. Kageyama et al., issued Aug. 17, 1993 and assigned to the assignee of the present application, and U.S. Pat. No. 5,370,471, S. Kageyama et al., issued Dec. 6, 1994 and assigned to the assignee of the present application, each discloses a mechanical pencil of rear-knock-type provided with a dispenser for selectively extending and retracting a stick-shaped object. The conventional mechanical pencil generally includes a barrel, a head member threadedly attached to a front end of the barrel, and a writing lead feeding mechanism in addition to the dispenser.
The lead feeding mechanism includes a sleeve, a chuck for releasably gripping a writing lead, the chuck having a forward enlarged head and a tubular section extending from the chuck head, and inserted in the sleeve with the chuck head projecting out of the sleeve, a chuck ring disposed around the chuck head, a writing lead tank having first and second ends, the writing lead tank connected at the first end thereof to the tubular section of the chuck, and a spring disposed within the sleeve to resiliently urge the writing lead tank rearwardly of the mechanical pencil.
The dispenser includes an outer tubular cap, an inner tubular body having first and second end portions, and a holder movably inserted in the first end section of the inner tubular body for holding a stick-shaped object. The holder has a pair of holding pieces and a projection provided on each of the holding pieces. The first end section of the tubular body is formed with a pair of axially extending slits in which respective ones of the holding pieces of the holder are slidably received. The outer tubular cap has a spiral groove formed in an inner surface section thereof. The first end portion of the inner tubular body, which has the holder incorporated therein, is fitted in the outer tubular cap with the projections of the holder being engaged with the spiral groove of the outer tubular cap. The second end portion of the inner tubular body is projected out of the outer tubular cap. An axial movement of the inner tubular body relative to the outer tubular cap is prevented but rotational movement of the inner tubular body relative to the outer tubular cap is allowed.
The dispenser is detachably attached to a rear end portion of the pencil barrel, having the writing lead feeding mechanism incorporated therein, with the second end section of the inner tubular body thereof being fitted on the second end portion of the writing lead tank in the pencil barrel and with the second end section of the tubular body thereof being fitted in the rear end portion of the pencil barrel. In the conventional mechanical pencil, axial movement of the dispenser relative to the pencil barrel is allowed but rotational movement of the inner tubular body of the dispenser relative to the pencil barrel is prevented.
In the mechanical pencil constructed as stated above, turning of the outer tubular cap causes the holder with the projections engaged with the spiral groove to be moved in an axial direction along the spiral groove, whereby the stick-shaped object held by the holder can be extended from or retracted into the rear end of the outer tubular cap in response to the turning of the outer tubular cap.
In the conventional mechanical pencil, the second end portion of the inner tubular body is connected to the second end of the writing lead tank. Advancing of a writing lead can be performed by knocking a rear end of the dispenser to thrust the writing lead tank forward against the action of the spring. The conventional mechanical pencil is of the rear-knock-type. There has not been yet proposed a writing instrument of side-knock-type or side-slide-type with a dispenser for selectively extending and retracting a substantially stick-shaped object.
With the conventional mechanical pencil constructed as stated above, the second end section of the inner tubular body of the dispenser is projected out of the outer tubular cap and the outer tubular cap of the dispenser is loosely mounted on the pencil barrel in order to ensure a smooth knocking operation of the dispenser relative to the pencil barrel and coupling between the pencil barrel and the dispenser is achieved only by causing the second end section of the inner tubular body of the dispenser to be fitted on the second end of the writing lead tank, so that there is a possibility that the second end section of the inner tubular body in the pencil barrel will be bent or broken when any external force is accidentlly applied to a region between the pencil barrel and outer tubular cap.